Electromagnetic coupling device



March 29,1949. B. PERKINS ELECTROMAGNETIC COUPLING DEVICE Filed Feb. 21, 1945 l m o We J l 2 P @nio i .y ;..J f 1 Fl a my F1 im W .nl L

Patented Mar. 29, 1949 UNITED STATES PATENT OFFICE ELECTROMAGNETIC CUUl-DLNG DEVICE Loya Bryan Perkins, Lufkin, TeX.

Application February 21, 1945, Serial No. 579,030

(Cl. F75- 359) 3 Claims. l

This invention appertains to inductance coil or transformer construction, particularly of the air core type for use in radio receiver and transmitter circuits, especially for first detector coupling, although adapted to be used for many other purposes, e. g., for interstage coupling when provided with an iron core.

One of the several objects of the invention is to provide aself-suppor-tng inductance couple, such a radio frequency transformer, in which the two windings are formed, with or without the use of .any of the usual foundation forms and with or without iron cores, and one of the windings is wound upon the other, or so wound in coi'itinuaA tion with. the other, in a manner to obtain the closest possible coupling and, at the same time, to eliminate a large percentage of the loss, due to leakage of the coils and material capacity, comn mon to many of the coil forms present in the prior art.

Another object of the invention has to do With the provision of a novel and highly eicient form of fixed inductance couple, or transformer, which involves a foundation coil, that is preferably bank wound to a selected diameter and circumferentially indented to form a selected number of radially extending projections or prongs, and a second, or cover, coil that is first wound to the form of a hat spiral and thereafter woven onto the projections or prongs, somewhat after the method involved in the forming of the diamond weave spiderweb coil.

`With 'these and other objects in view, the invention resides in the certain new and useful combination, construction, and arrangement of coils, as will be hereinafter more fully described, set forth in the appended claims, and illustrated in the accompanying drawing, in which:

Figure l is a top plan view of the inductance couple or transformer, in accordance with the invention;

Figure 2 is a cross section through two adjacent projections or prongs ofthe foundation coil, showing the diamond lweave of the cover coil thereon;

Figure 3 is a cross section taken through the line 3 3 on Figure 2, showing the close winding of a layer of turns or convolutions of the cover coil;

Figure 4 is a cross section taken diametrically through the cover coil, prior to its assembly on the foundation coil;

Figure 5 is an enlarged perspective detail of one of the projections or prongs of the foundation coil, and showing the interweaving therewith of two adjacent turns or convolutions of the cover coil; and

Figure 6 is a view similar to that of Figure 2, but showing a circular weaving of the cover coil turns or convolutions about two adjacent projections or prongs of the foundation coil.

Referring to the drawing, wherein like characters of reference denote corresponding parts in the several views, the preferred embodiment of the invention, as it is exemplified in Figures 1 through 5, comprised in a foundation coil l0, constituting the primary winding of the inductance couple or transformer, which is rst wound to the form of a plain cylindrical coil having several layers of turns or convolutions one over the other, three of such layers being shown for the purposes of the present description. If the coill is formed as a plain layer winding, instead of being bank wound, there would be a considerable capacity effect, since the rst and last turns would come together. Hence, t0 avoid this ex-L cessive distributed capacity, the bank type winding is much to be preferred, although for certain purposes, the plain layer Winding may be resorted to.

Upon the completion of the cylindrical coil foundation, it is circumferentially indented to provide a selected number of equidistantly spaced, radially extending, projections or prongs .I 2, thirteen ofthe same being shown in Figure 1y of the drawing, and, thereafter, a cover coil I8, constituting the secondary Winding of the inductanee couple or transformer, is applied to the projections or prongs, preferably, by a method somewhat similar to that employed in the formation of a diamond weave spider web coil. In the forming of the cover coil i8, it is first wound to the shape of a flat spiral and thereafter its several turns or convolutions are woven onto the projections or prongs l2, in the stated manner. By

thus Weaving the cover coil i8, it retains all of the advantages of a flat spiral winding, While doing away with the disadvantages thereof. In Figure l, the terminal ends of the foundation coil il! are indicated at i4 and l5, and those of the cover coil i3, at 20 and 22.

The coil assembly, thus provided, may be employed as an air core inductance couple or transformer, or it may be provided with an iron core (not shown), either solid or laminated, as desired. In the latter case, the core may take the form of a disc, or a disc assembly if laminated, having projections or prongs fitting into the projections or prongs l2, of the foundation coil se I0.

For radio receiver antenna coupling, I prefer to have the foundation coil IIJ made up of eighteen (18) turns on a four (4) inch diameter, the terminals I 4 and i5 connecting the antenna and ground, while the cover coil Iii of half that number of turns and reversely wound, with its terminals 28 and 22 connecting ground to B-. However, the cover coil I8 may be wound in the same direction as is the foundation coil I0, with equally good results, using the same terminal hookup. In designing the inductance couple or transformer for this purpose, it will be understood that the range of reception of broadcast signals will Vary with the number of projections or prongs I2 provided on the foundation `coil I0, i. e., the fewer the projections or prongs, the lesser the number of stations to be brought in.

For interstage and like coupling, I make the foundation coil ID up with twenty-four (24) turns on a three and one-half (3l/2") inch diameter, while the cover coil I8 may be made up of any lesser of turns, depending upon the B of plate voltage. When the foundation coil I0 is initiallyT wound to cylindrical form, the plate reading should be zero, and when indented to form the projections or prongs I2, a plate gain of approximately one-half is obtained. Likewise, upon the completion of the cover coil I8, the plate reading should also read zero, or nearly so. If the inductance value of the cover coil I8 is made to match that of the foundation coil Iii, the transformer functions to pass any frequency within its band. However, it is also to be understood that, depending upon the intended use of a couple or transformer, the cover coil I8 can be proportioned relatively to the foundation coil II), i. e., from less than half length to an over length. In any case, the magnetic field of the foundation coil I0 is compressed, while that of the cover coil I8 is spread, the relationship of the two fields being that of rotation with the current impulse or movement within them, unless the reverse condition is required for a particular circuit arrangement.

the cover coil I3 with the foundation `coil I0 is illustrated and, here, each turn, or convolution, of the cover coil is looped about each of the projections or prongs I2 of the foundation coil. By making these loops I8" to circular form, i

they are to be engaged over the projections or prongs I2 with a facility substantially equal to that of the interweaving or" the turns or convolutions, as in the iirst instance.

In the design of these inductive couplings, or transformers, it is to be understood that the depth of the indentations, for forming the projections or prongs I2, I2' in the foundation coil IIJ, will determine the angular torque of the two coil relationship, i. e., of the magnetic fields thereof, and, also, effect the direction of wind. With the coils I0 and I8 meshing as shown, the angle of approach of the two fields is variable and the degree of that angle determines the electronic angular collision of the elds, which can be headon, or sidewise, i. e., parallel; a compound torque effect being involved in either or both. With the use of a crystal detector, the two coils must be matched by touch units, i. e., self-inductance units.

From the foregoing description of my invention, it will be evident to those skilled in the radio art that these forms of inductance couples, or transformers, makes for the highest value of mutual inductance, by reason of the closeness of association of the cover coils I8, I8', with the foundation coils IIJ, Ill', and, also, the coincidence of their axes, which value, however, is subject to variation .by changes in sizes, diameters, and length, of the two coils, .as is well understood.

Having thus fully described my invention, it is to be understood that the disclosed coils constructions are subject to any and all modication that may fall within the scope of the apf pended claims.

I claim:

1. In a transformer, a first winding comprising a circular turn of wire wound substantially in a plane with radially extending convolutions therein, each convolution comprising an outwardly extending portion and an inwardly returning portion of the wire, and a second winding electrically insulated from the first winding and electromagnetically coupled thereto comprising a further wire wound substantially in the form of a ilat helix and extending alternately over and under both portions of each successive convolution.

2. In a transformer, a first winding comprising a circular turn of wire wound substantially in a plane with an odd number of radially extending convolutions therein, each convolution comprising an outwardly extending portion and an in wardly returning portion of the wire, and a sec ond winding mechanically supported by the first winding, electrically insulated therefrom, and electromagnetically coupled thereto comprising a further wire wound substantially in the form of a flat helix extending alternately over and under .-1.1 both portions of each successive convolution.

3. In a transformer, a rst winding comprising a plurality of circular turns of wire closely grouped together wound substantially in a plane and with an odd number of radially extending In Figure 6, a modied method of associating convolutions therein, each convolution comprising adjacent outwardly extending portions and adjacent inwardly returning portions of the wire of the plurality of turns, and a second winding mechanically supported by the first winding, electrically insulated therefrom, and electromagnetically coupled thereto comprising a. further wire wound substantially in the form of a fiat helix and extending alternately over and under both portions of each successive convolutions.

LOYA BRYAN PERKINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,615,755 Grave Jan. 25, 1927 1,672,889 Ide June 12, 1928 1,827,191 Casper Oct. 13, 1931 FOREIGN PATENTS lilunjber Country Date 123,346 Great Britain Jan. 29, 11919 319,167 Great Britain Sept. 19, 1929 

